U.S. patent application number 15/218469 was filed with the patent office on 2016-11-17 for variable stiffness guidewire.
The applicant listed for this patent is Lake Region Manufacturing, Inc.. Invention is credited to Jeanne Douglas, Chris Minar, Andrew Senn.
Application Number | 20160331942 15/218469 |
Document ID | / |
Family ID | 35782305 |
Filed Date | 2016-11-17 |
United States Patent
Application |
20160331942 |
Kind Code |
A1 |
Minar; Chris ; et
al. |
November 17, 2016 |
VARIABLE STIFFNESS GUIDEWIRE
Abstract
This invention includes a highly torqueable, pushable guidewire
with a relatively stiff proximal (preferably in one embodiment),
stainless steel (SS) section and kink resistant nitinol medial to
distal section attached to a shapeable SS, in one embodiment, (such
as a SS ribbon) distal tip. The very distal SS tip will have the
ability to be shaped by the end user in order to facilitate entry
into the chosen vessels.
Inventors: |
Minar; Chris; (New Prague,
MN) ; Douglas; Jeanne; (Shakopee, MN) ; Senn;
Andrew; (Chanhassen, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lake Region Manufacturing, Inc. |
Chaska |
MN |
US |
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|
Family ID: |
35782305 |
Appl. No.: |
15/218469 |
Filed: |
July 25, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14709066 |
May 11, 2015 |
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15218469 |
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11159040 |
Jun 22, 2005 |
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14709066 |
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60582033 |
Jun 22, 2004 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 2025/0915 20130101;
A61M 2025/09083 20130101; A61M 2025/09141 20130101; A61M 25/09
20130101; A61B 1/01 20130101; A61M 25/09033 20130101; A61M
2025/09133 20130101; A61M 2025/09175 20130101; A61M 25/0054
20130101; A61M 2025/09166 20130101 |
International
Class: |
A61M 25/09 20060101
A61M025/09; A61M 25/00 20060101 A61M025/00 |
Claims
1. A variable stiffness guidewire, comprising: a) a core element
comprising a proximal core portion and a distal core portion,
wherein the distal core portion comprises at least a first sidewall
of a first diameter extending distally to a tapered section meeting
a second sidewall of a second diameter, the second diameter being
less than the first diameter; and b) a first spring coil extending
from a first spring coil proximal portion to a first spring coil
distal end, wherein the first spring coil proximal portion contacts
at least the first sidewall of the first diameter of the distal
core portion, and wherein the first spring coil distal end is
proximal the distal end of the distal core portion; and c) a second
spring coil extending from a second spring coil proximal portion to
a second spring coil distal end; and d) a distal atraumatic tip, e)
wherein the second spring coil proximal portion contacts the first
spring coil distal end, and f) wherein the second spring coil
extends distally beyond the distal end of the distal core portion
of the core element with the second spring coil distal end
connected to the distal atraumatic tip.
2. The guidewire of claim 1 wherein the proximal core portion of
the core element comprises stainless steel.
3. The guidewire of claim 1 wherein the second spring coil proximal
portion either overlaps or is interwoven with the first spring
coil.
4. The guidewire of claim 1 wherein a non-super elastic shaping
ribbon is attached to the distal core portion of the core element,
and wherein the shaping ribbon is disposed inside at least the
second spring coil and extends distally beyond the distal end of
the distal core portion to connect to the distal atraumatic
tip.
5. The guidewire of claim 1 wherein the distal nitinol core portion
has a composition in the range of from about 54 atomic % nickel:
about 46 atomic % titanium to about 57 atomic % nickel: about 43
atomic % titanium.
6. The guidewire of claim 1 wherein the first spring coil is of a
non-radiopaque material and the second spring coil is of a
radiopaque material.
7. The guidewire of claim 6 wherein the first radiopaque spring
coil and the second non-radiopaque spring coil either overlap or
are interwound with each other.
8. A variable stiffness guidewire, comprising: a) a core element
comprising a proximal stainless steel core portion and a distal
nitinol core portion, wherein the distal nitinol core portion
comprises at least a first sidewall of a first diameter extending
distally for a first length to a tapered section meeting a second
sidewall of a second diameter extending for a second length, the
second diameter being less than the first diameter; b) a first
spring coil extending from a first spring coil proximal portion to
a first spring coil distal end, wherein the first spring coil
proximal portion contacts at least a portion of the first length of
the first sidewall of the first diameter of the distal nitinol core
portion, and wherein the first spring coil distal end is proximal
the distal end of the distal nitinol core portion; c) a second
spring coil extending from a second spring coil proximal portion to
a second spring coil distal end; and d) a distal atraumatic tip, e)
wherein the second spring coil proximal portion contacts the first
spring coil distal end, and f) wherein the second spring coil
extends distally beyond the second length of the second sidewall of
the distal nitinol core portion of the core element with the second
spring coil distal end connected to the distal atraumatic tip.
9. The guidewire of claim 8 wherein the core element terminates
proximally with respect to the atraumatic tip.
10. The guidewire of claim 8 further comprising a non-super elastic
shaping ribbon attached to the distal nitinol core portion of the
core element, wherein the shaping ribbon is disposed inside at
least the second spring coil and extends distally beyond the distal
end of the distal nitinol core portion of the core element to
connect to the distal atraumatic tip.
11. The guidewire of claim 10 wherein the shaping ribbon comprises
stainless steel.
12. The guidewire of claim 8 wherein the first spring coil is of a
non-radiopaque material and the second spring coil is of a
radiopaque material, and wherein the respective first and second
non-radiopaque and radiopaque spring coils either overlap or are
interwound with each other.
13. The guidewire of claim 8 wherein the distal nitinol core
portion has a composition in the range of from about 54 atomic %
nickel: about 46 atomic % titanium to about 57 atomic % nickel:
about 43 atomic % titanium.
14. A variable stiffness guidewire, comprising: a) a core element
comprising a proximal core portion and a distal nitinol core
portion, wherein the distal nitinol core portion comprises at least
a first sidewall of a first diameter extending distally for a first
length to a tapered section meeting a second sidewall of a second
diameter extending for a second length, the second diameter being
less than the first diameter; b) a coupler connecting the proximal
core portion to the distal nitinol core portion; and c) a first
spring coil extending from a first spring coil proximal portion to
a first spring coil distal end, wherein the first spring coil
proximal portion contacts at least a portion of the first length of
the first sidewall of the first diameter of the distal nitinol core
portion, and wherein the first spring coil distal end is proximal
the distal end of the distal nitinol core portion; and d) a second
spring coil extending from a second spring coil proximal portion to
a second spring coil distal end; and e) a distal atraumatic tip, f)
wherein the second spring coil proximal portion contacts the first
spring coil distal end, and g) wherein the second spring coil
extends distally beyond the distal end of the distal nitinol core
portion of the core element with the second spring coil distal end
connected to the distal atraumatic tip.
15. The guidewire of claim 14 wherein the proximal core portion
comprises a non-super elastic alloy.
16. The guidewire of claim 14 wherein the second spring coil
comprises platinum.
17. The guidewire of claim 14 wherein the first spring coil is of a
non-radiopaque material and the second spring coil is of a
radiopaque material, and wherein the respective first and second
non-radiopaque and radiopaque spring coils either overlap or are
interwound with each other.
18. The guidewire of claim 14 wherein the distal nitinol core
portion has a composition in the range of from about 54 atomic %
nickel: about 46 atomic % titanium to about 57 atomic % nickel:
about 43 atomic % titanium.
19. A variable stiffness guidewire, comprising: a) a core element
comprising a proximal core portion and a distal nitinol core
portion, wherein the distal nitinol core portion comprises at least
a first sidewall of a first diameter extending distally to a
tapered section meeting a second sidewall of a second diameter, the
second diameter being less than the first diameter; and b) a first
spring coil extending from a first spring coil proximal portion to
a first spring coil distal end, wherein the first spring coil
proximal portion contacts at least the first sidewall of the first
diameter of the distal nitinol core segment, and wherein the first
spring coil distal end is proximal the distal end of the distal
nitinol core segment; and c) a second spring coil extending from a
second spring coil proximal portion to a second spring coil distal
end; and d) a distal atraumatic tip, e) wherein the second spring
coil proximal portion contacts the first spring coil distal end,
and f) wherein the second spring coil distal end and the distal end
of the distal nitinol core portion of the core element both connect
to the distal atraumatic tip.
20. The guidewire of claim 19 wherein a non-super elastic shaping
ribbon is attached to the distal nitinol core portion of the core
element, and wherein the shaping ribbon is disposed inside at least
the second spring coil and is connected to the distal atraumatic
tip.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/709,066, filed on May 11, 2015, which is a
continuation of U.S. patent application Ser. No. 11/159,050, filed
on Jun. 22, 2005, now abandoned, which claims priority to U.S.
provisional patent application Ser. No. 60/582,033, filed on Jun.
22, 2004.
BACKGROUND OF THE INVENTION
[0002] In general, guidewires for medical procedures such as
angioplasty, are made with stainless steel wire (SS) which, when
ground in a series of tapers and straights, generally decreases
from a proximal core body diameter of 0.014 inches down to a distal
diameter of approximately 0.002 inches. A portion of this ground
section of core, possibly including a ribbon wire, will be covered
with one or more coils.
[0003] Some disclosures describe guidewire with nitinol distal
portions that yield at a desired set shape (U.S. Pat. No.
5,238,004) and consist of a SS proximal section attached to a
linear elastic distal section. (The teachings of the '004 patent
are incorporated herein by reference). This layout of the '004
patent has a lower kink resistance than the proposed invention.
[0004] Other disclosures (e.g., U.S. Pat. No. 6,592,570) involve a
SS proximal section and a distal portion that is entirely
superelastic. (The teachings of the '570 patent are incorporated
herein by reference). This superelastic distal tip restricts
shapeability and can cause the placement of the guidewire into a
vessel to be difficult. The proposed invention is kink resistant,
yet it has a shapeable tip that will assist the user in negotiation
of vessels.
[0005] A stainless steel body proximal guidewire gives exceptional
column strength to push, support catheters, and torque the distal
end of the guidewire through the vessel. A nitinol ground middle to
distal section is flexible enough to avoid damaging the vessel
during advancement of the guidewire. The shortcoming to a stainless
steel distal section is that it can bend and kink during
advancement, making it difficult to advance into the chosen vessel.
Current guidewires made of a SS proximal portion and superelastic
nitinol distal portion have a transition in a step or discrete
fashion, making for potentially difficult navigation. Other
guidewires made of a SS proximal section and a linear elastic
nitinol distal section transition more smoothly, but are less kink
resistant at the distal tip. For these reasons a kink resistant
guidewire that decreases gradually in stiffness from the proximal
to the distal end i.e., a variable or gradually decreasing
stiffness guidewire, is ideal.
SUMMARY OF THE OF INVENTION
[0006] By attaching a nitinol distal ground section to the
stainless steel proximal core wire or element of a guidewire the
propensity of the distal flexible section to bend and kink is
reduced. This invention includes a highly torqueable, pushable
guidewire with a relatively stiff proximal (preferably in one
embodiment), stainless steel (SS) section and kink resistant
nitinol medial to distal section attached to a shapeable SS, in one
embodiment, (such as a SS ribbon) distal tip. The very distal SS
tip will have the ability to be shaped by the end user in order to
facilitate entry into the chosen vessels.
[0007] It is the purpose of this invention to provide an improved,
kink resistant guidewire. This is best achieved by gradually
decreasing the stiffness from the proximal to the distal end by
using, for example, a combination of SS and variably heat-treated
nitinol.
[0008] The novelty of this invention involves the combination of
different metals and elementally similar metals in different phases
to attain ideal guidewire characteristics.
[0009] Thus, in one embodiment, the present invention is a variable
stiffness guidewire comprising:
[0010] a core element or core wire having proximal and distal
portions, the distal portion having proximal and distal segments,
the distal segment of the core element comprising nitinol, the
nitinol being at least partially linear elastic in the proximal
segment of the distal portion, and super elastic in the distal
segment of the distal portion.
[0011] In a further embodiment, the present invention is a variable
stiffness guidewire comprising a core element or wire having a
proximal portion and a distal portion, the distal portion having
distal and proximal segments and the proximal portion having distal
and proximal segments:
[0012] the core element proximal portion comprising stainless
steel;
[0013] the core element distal portion comprising;
[0014] a superelastic distal segment and a linear elastic proximal
segment, the core element having attached to its extreme distal
end;
[0015] an atraumatic tip.
[0016] In yet another embodiment, the present invention is a
variable stiffness guidewire comprising a core element having
proximal and distal portions comprising different materials:
[0017] the proximal portion including a reduced-diameter distal
section;
[0018] the distal portion including a reduced-diameter proximal
section;
[0019] a hollow coupler connecting the reduced-diameter distal
section of the proximal portion to the reduced-diameter proximal
segment of the distal portion, wherein the proximal portion
comprises a non-super elastic alloy; and the distal portion
comprises nitinol in a linear elastic state on its proximal segment
and a nitinol in super elastic reduced-diameter distal segment.
[0020] Stiffness is variable or is gradually decreased or
decreasing by assembling a SS proximal section to a nitinol distal
section, which is attached to an independent or attached SS tip.
More specifically, the nitinol distal portion comprises a linear
elastic nitinol proximal segment and a super elastic nitinol distal
segment. The nitinol distal segment is attached to, e.g., an SS
proximal portion or segment. This graduation from linear elastic
nitinol to superelastic nitinol creates an advantageous, gradual,
and controlled or controllable reduction or decrease in guidewire
stiffness (in accordance with this invention) when moving distally
from the proximal segment to the distal segment to create a kink
resistant guidewire. The combination of this two-phase, distal
nitinol section and the stiff proximal 304 stainless steel section
along with the optional shapeable SS distal portion (i.e., a
shaping ribbon) creates the ideal torqueable, pushable, and
steerable guidewire having varying or distally-decreasing
stiffness.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 where shown, in section, a finger-formable version of
the present invention in which the superelastic distal segment of
the core wire or core element extends distally from before the
first taper (shown by shading) all the way to the end of the core
wire, which terminates short of the extreme distal tip;
[0022] FIG. 2 is an embodiment of the present invention in which
the superelastic distal portion begins adjacent to the first core
wire taper (shown by shading) and extends to the end of the core
wire, which also terminates short of the guidewire distal tip;
[0023] FIG. 3 is an embodiment to the present invention in which
the superelastic core wire segment begins distal to the first core
wire taper (shown by shading) and extends to the end of the core
wire which also terminates short of the guidewire extreme distal
tip;
[0024] FIG. 4, FIG. 5 and FIG. 6 are non-tip formable embodiments
of the present invention in which the zones of superelastic core
wire begin at the same points as shown in FIGS. 1, 2 and 3,
respectively and the core wire or core element extends all the way
to the guidewire tip.
[0025] FIG. 7 shows in section an embodiment to the present
invention in which the superelastic distal segment extends all the
way to the extreme distal tip of the guidewire and in which the
guidewire is also tip formable.
[0026] FIG. 8 is a stress/strain curve (to break) of the materials
indicated thereon.
[0027] FIG. 9 is displacement vs. load.
DETAILED DESCRIPTION OF THE INVENTION
[0028] This invention is, in one embodiment, a Dual Phase Nitinol
PTCA Guidewire (see attached FIGS. 1-7) with a stainless steel
proximal shaft 1 and a nitinol medial to distal section 2
(generally, the length indicated by "C") attached by a nitinol hypo
tube 3. This nitinol middle section is then attached to a SS distal
tip 11. Distal tip 11 is attached to the nitinol section 2 by means
of a spring coil 5, 7 and a ribbon wire or safety ribbon 4. Spring
coil 5, 7 comprises a radiopaque segment 7 and a non-radiopaque
segment 5 which overlap or are interwound and are soldered together
at 12. The embodiment shown has two tapered or ground section 20,
21. Other combinations of tapered, ground, or flattened guidewire
sections are within the contemplation of this invention.
[0029] The invention encompasses a range of constructions from
floppy to extra support grind configurations. The invention
preferably is built in 190 cm length and 300 cm length
configurations with a preferred maximum diameter of 0.014''. The
proximal core segment 1 is preferably PTFE coated and the distal
segment 2 preferably is coated with a separate lubricious coating
e.g., silicone, or other hydrophilic coating. The hydrophilic
coating commercially available from Surmodics Corp. is preferred.
The invention contemplates an optional extension system to be used
with the 190 cm wire version having a proximal connector structure
6. As was noted a platinum distal marker coil 7 is threaded into a
coil spring 5 and optional proximal depth marks on the optional
PTFE-coated proximal section 8 are placed using e.g., an emulsion
ink.
[0030] The nitinol middle section "C" will consist of a proximal
linear elastic segment 9, which will graduate into a superelastic
(heat-treated) segment 10 indicated by shading in all the FIGURES.
The superelastic segmnet 10 is created by placing the desired
length of core wire segment in an oven at about 1000.degree. F. for
20 minutes. There will be a slight transition created between the
linear elastic and superelastic segments that will aid in a gradual
transition of lowered stiffness contributing to the variable
stiffness feature of this invention. One skilled in this art will
appreciate that either or both of the time of treatment or
temperature of treatment of the core wire may be adjusted to obtain
the requisite superelasticity. This transition length can be easily
optimized to improve the overall properties of the guidewire. Other
linear elastic sections may be heat-treated at lower temperatures
to create more elasticity/less stiffness and a more gradual
transition. (see attached test data for stiffness variations)
[0031] It has also been determined that the nitinol wire section 2
included in this invention has the ability to be straightened
mechanically or by providing tension during the heat-treatment.
These operations also create variable elasticity and could be used
in the gradual reduction of stiffness along the guidewire.
[0032] A process has been developed that involves the heat
treatment of linear elastic NiTi. The linear elastic core is placed
in an oven at about 950.degree. F. for 25 minutes with no
longitudinal tension which causes the extreme distal portion of the
guidewire to become superelastic. The oven is constructed in a way
so that there is a void or hole in the wall of the oven where a
wire can be placed. The NiTi core is inserted in to the void so
that the desired length of super elastic NiTi is fully inside the
oven. The heat dissipation leaving the void of the oven produces a
smooth stiffness and elasticity transition from the linear to
superelastic region. Stress vs. strain results, have been measured
and a gradual drop in stiffness from the linear elastic region to
the superelastic region is clearly apparent using the
above-described process. In this manner, the overall stiffness of
the guidewire may be controlled by controlling the length of the
core wire superelastic segment.
[0033] Thus, there is shown at FIGS. 1-7, in section, several
embodiments of the present invention. It is to be understood that
in each of these embodiments a distal portion of a guidewire core
wire 2 comprises a more distal superelastic segment 10 and a more
proximal linear elastic segment 9. In a preferred embodiment, the
distal core wire or element comprises a nickel titanium alloy
having a composition in the range of from about 54 atomic % nickel
to 46 atomic % titanium to about 57 atomic % nickel to about 43
atomic % titanium.
[0034] In FIG. 1 there is shown an embodiment of the invention in
which there is a hydrophobically-coated, e.g., PTFE, stainless
steel proximal guidewire/core wire segment and a distal linear
elastic 9/super elastic 10, (shown by shading) core wire segment 2,
the core wire terminating short of the extreme distal tip of the
guidewire. The hydrophobic coating on the proximal segment of the
guidewire preferably comprises PTFE. Various other hydrophobic
coatings will readily come to mind to one skilled in this art in
view of this disclosure. As is shown, the extreme proximal portion
of the proximal guidewire segment may be coated (shorter lengths)
or lack coating so as to permit the guidewire to be more easily
handled.
[0035] The proximal portion (approximately the "G" dimension minus
the "B" dimension) and distal segment 2 are shown to be coupled by
a hypotube connector 3, each such segments having reduced diameter
portions 22, 23 which are inserted into opposite ends of the
hypotube connector 3 and are bonded thereto e.g., by the use of
solder or glue. The hypotube connector 3 may comprise stainless
steel, linear elastic or superelastic alloys depending upon design
preference. Other equivalent means of creating a coupler between a
stainless steel proximal segment and a linear elastic/super elastic
distal segment will occur to one skilled in this art in view of the
present disclosure c.f., U.S. Pat. No. 5,341,818 Abrams et al., the
teachings of which are incorporated by reference herein.
[0036] There are other guidewire optional features shown in FIG. 1.
For example, a spring coil is shown to be attached to the first
core wire taper on its proximal end and to the guidewire tip 11 on
the distal end. The spring coil extends distally to a point where
the stainless steel coil 5 ("SS coil") is inter-wound with a
platinum core wire 7 and soldered or glued thereto 12. As is shown
the platinum coil wire is inter-wound with the stainless steel coil
a length sufficient to provide an aggressive yet flexible (so as
not to create a flat spot) connection. Also optionally included in
this embodiment of the invention is a generally flat stainless
steel ribbon wire 4 soldered (or otherwise attached) to the core
wire which extends distally to the atraumatic, extreme guidewire
tip. The ribbon wire imparts finger formability to the distal
segment of the guidewire.
[0037] FIGS. 2 and 3 depict variations of the invention shown in
FIG. 1, the primary difference being that the shaded superelastic
segment 10 begins at a zone or region that is distally-disposed
relative to the comparable superelastic segment shown in FIG. 1. In
FIG. 2 the superelastic segment 10 begins adjacent the first taper
20 of the guidewire distal segment. In FIG. 3 the superelastic
segment 10 (shaded), is distally located from the comparable
structures shown on FIGS. 1 and 2. The shorter superelastic zones
or portions of the guidewires shown in FIGS. 2 and 3 mean that the
distal portion of the guidewire is increasingly less "floppy" or
conversely, stiffer. In each of the guidewires depicted in FIGS. 1,
2 and 3 a finger-formable ribbon wire 4 is used to impart finger
formability to the distal segment of the guidewire. In this manner
the medical professional using the guidewire may impart a desired
bend or deviation from linearity, which will be retained by the
guidewire, depending upon the user's personal preference.
[0038] FIG. 4 depicts the guidewire of the present invention in
which the distal portion of the guidewire does not have the
optional flat stainless steel ribbon wire or safety wire extending
between the guidewire core and the atraumatic guidewire extreme
distal tip. Also, the superelastic core wire or core element
extends all the way to the atraumatic tip of the guidewire and is
surrounded by a stainless steel/platinum spring coil 5, 7. The
absence of the ribbon wire/safety wire means that the distal
portion of the guidewire shown in FIG. 4 will not be easily finger
formable. Put otherwise, the superelastic characteristics of the
distal portion of the core wire will prevent it from easily
retaining a bend or lateral displacement imparted thereto.
[0039] FIGS. 5 and 6 depict the guidewire shown in FIG. 4 with
distally-disposed, shorter superelastic core wire segments 10. All
other features of the guidewires of FIGS. 5 and 6 are the same as
that of FIG. 4.
[0040] FIG. 7 shows a further embodiment to the present invention
in which the superelastic core wire extends all the way to the
atraumatic distal tip and a ribbon wire or safety wire 4 also is
employed. The guidewire shown in FIG. 7 is otherwise the same as
the guidewires shown in FIGS. 1-6.
[0041] It is to be understood that the controllable or variable
stiffness of a guidewire of the present invention may also be
varied or adjusted by employing one or more distal tapers. The
guidewires in FIGS. 1-7 all are shown to employ two such tapers 20,
21. Clearly, the number of tapers employed, their location and
their length is a matter of design preference depending upon the
extent of stiffness (or flexibility) to be imparted to the
guidewire.
[0042] It is also to be understood that the dimensions shown for
the guidewires in FIGS. 1-7 are not to be employed to limit the
scope of the present invention. Without being limited thereto,
dimensions shown by the use of letters in FIGS. 1-7 generally fall
in the following range(s):
Drawing Letter
TABLE-US-00001 [0043] Designation Structure Range A. Length of
hypotube 2-10 cm B. Length of hydrophilic coat 2-100 cm C. Length
of guidewire distal segment 10-60 cm G. Overall guidewire length
70-320 cm
[0044] FIGS. 8 and 9 show the relationship between, non-super
elastic, super elastic and linear elastic core wire or core element
materials as a function of stress vs. strain (to break) FIG. 8, and
load vs. displacement (cross head inches). Those FIGURES show the
definite performance differences between the alloys and alloy
states used in the present invention.
[0045] The above invention has been described with particular
reference to the use of a nickel/titanium alloy to create the
guidewire of variable stiffness herein described. The present
invention should not be understood to be limited only to the use of
nickel/titanium alloys. In fact, any alloy exhibiting the
superelastic/linear elastic characteristics of nickel/titanium
alloys employed herein is clearly contemplated. Thus, the present
invention is not, and should not, be construed to be limited to the
preferred nickel/titanium alloys extensively discussed herein.
* * * * *